Preparation of tailor-made starch-based aerogel microspheres by the emulsion-gelation method

The inherent biocompatibility and biodegradability of starch, a natural polysaccharide-based product, allows its use in the form of microspheres as a chemical carrier for life science applications. However, current methods of preparation of starch microspheres utilize chemical crosslinkers and drying methods (air drying, freeze drying) that leads to problems of degradability of the matrix and low specific surface areas and chemical loading capacities. In this work, corn starch aerogel microspheres, a special class of nanoporous materials, were prepared by the combination of an emulsion-gelation method and supercritical drying without the use of chemical crosslinkers. Effects of gelation temperature (368, 393 and 413 K), oil-to-aqueous starch solution ratio (1:1, 2:1, 3:1) and surfactant content (3, 6 and 10% (w/w)) on the textural and morphological properties of the aerogel material were studied. The obtained starch aerogels were characterized using nitrogen adsorption–desorption measurements, helium pycnometry, CHN elemental analyses, thermogravimetry and scanning electron microscopy. Spherical starch aerogel microspheres with tailor-made specific surface areas (34–120 m2 g−1 range) and particle sizes (215–1226 μm diameter range) were obtained. Aerogel textural properties were mainly influenced by the gelation temperature used, whereas the particle morphology depended on the three processing parameters studied. High specific chemical loading capacity (1.1 × 10−3 g m−2) of the aerogel microspheres was obtained using ketoprofen as a model compound.